The major objective of the proposed research is to determine the residual effects of low level lead exposure on the fetal and infant rhesus monkey. Pregnant rhesus monkeys will be fed low levels of lead throughout gestation and their infants evaluated biologically and behaviorally during infancy, adolescence, and early adulthood. Similar studies will also be conducted on infant monkeys that are exposed to low levels of lead during the initial year of life. These studies will help to clarify the effects of lead exposure during early life on the subsequent development of the infant. In addition, maximum tolerable levels of lead administered over a given period to fetal (via the mother) and infant monkeys will be established. The methods that will be employed in evaluating these animals will include behavioral studies that will emphasize social interaction and learning capabilities of these animals from birth to adulthood. The clinical studies conducted will be systematic hematological, radiological, and biochemical determinations throughout infancy, adolescence, and adulthood. After the completion of the clinical and behavioral studies histological and ultrastructural studies will be conducted on all of the major organs. In addition, total concentrations of lead in various tissues of the body will be determined.